Cooling medium-moving devices for gas-liquid contacting apparatus

ABSTRACT

The operating fluid supply means for the fan-driving turbine of a cooling medium-moving device for a gas-liquid contacting apparatus comprises a plurality of supply pipes, one of which is designed to supply fluid to a main nozzle or nozzles to effect the operation of the turbine and the other or others of which is/are designed to supply fluid to a secondary nozzle or nozzles to assist the driving of the turbine and/or is/are provided with a fluid outlet aperture or apertures, the fluid issuing from which does not assist in driving the turbine, whereby the operating fluid may be selectively distributed amongst any one or more of said pipes so as to vary the speed of rotation of the turbine as desired.

United States Patent Murphy [1 1 3,669,421 1 June 13, 1972 1 1 COOLING MEDIUM-MOVING DEVICES FOR GAS-LIQUID CONTACTING APPARATUS [72] Inventor:

[73] Assignee:

Edmund Murphy, La Spezia, ltaly Cooling Developments Ltd., Luceme, Switzerland [22] Filed: March 6, 1970 [21] Appl. No.: 17,068

[30] Foreign Application Priority Data March 24, 1969 Great Britain ..15,194/69 [52] U.S.Cl .t261/25,415/63,415/101, 55/226, 261/67, 261/88, 261/89,261/1l1, 261/DlG. 11 [51] Int. Cl. ..B0ll3/04 [58] Field ot'Search ..26l/25, 111,67, 88, 89, DIG. 11; 415/101, 63; 55/226 [56] References Cited UNlTED STATES PATENTS 3,253,819 5/1966 Talbot ..261/25 1,225,844 5/1917 Mueller ..415/101 2,695,773 1 H1954 McGrath ..261/25 3,195,870 7/1965 Gruber et al..... ...,261/25 655,121 7/1900 Schafi'stadt ..261/25 621,718 3/1899 Seymour, .Ir. ..261/25 X 2,672,328 3/1954 Mart et a1. ..261/25 FOREIGN PATENTS OR APPLICATIONS 9,742 10/1904 Great Britain t ..261/25 25,053 9/ 1909 Great Britain ..261/25 Primary Eraminer-Tim R. Miles Anorney-Baldwin, Wight, Diller & Brown 1 1 ABSTRACT The operating fluid supply means for the fan-driving turbine of a cooling medium-moving device for a gas-liquid contacting apparatus comprises a plurality of supply pipes, one of which is designed to supply fluid to a main nozzle or nozzles to effect the operation of the turbine and the other or others of which is/are designed to supply fluid to a secondary nozzle or nozzles to assist the driving of the turbine and/or is/are provided with a fluid outlet aperture or apertures, the fluid issuing from which does not assist in driving the turbine, whereby the operating fluid may be selectively distributed amongst any one or more of said pipes so as to vary the speed of rotation of the turbine as desired.

7 Claims, 4 Drawing Figures COOLING MEDIUM-MOVING DEVICES FOR GAS- LIQUID CONTACTING APPARATUS This invention relates to improvements relating to gas-liquid contacting apparatus. such, for example, as a water cooling tower and more particularly concerns cooling medium-moving devices for use therewith and comprising at least one fluidoperated turbine and a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus.

BACKGROUND OF THE INVENTION It has already been proposed to use with a water cooling tower a gasor air-moving device of the above kind in which the turbine is operated by the fluid, such as water, to be treated in the cooling tower, the fluid being supplied to the turbine under pressure to effect rotation of the turbine, and thus rotation of the fan coupled thereto, prior to its passage through the cooling tower.

While such an arrangement will be found to operate satisfactorily under normal temperature conditions, it is clearly desirable, under certain circumstances, such as, for example, where the plant is operating under very low temperature conditions liable to cause icing-up, to be able to reduce the rapidity of cooling by reducing the rate of rotation of the turbine rotor and thus of the fan and thereby reducing the flow of air or other cooling gas through the tower.

As it is generally preferable and, in some instances, a requirement of the process from which the fluid to be treated is derived, that the flow of such fluid to the cooling tower shall remain substantially constant, it has been suggested to achieve the requisite reduction in speed of the turbine rotor by bypassing part of the fluid flow before it reaches the turbine and allowing it to pass uncooled to the bottom of the tower.

Such a procedure, while achieving the immediate result of reducing the speed of air-flow, is obviously uneconomic both from the point of view of unnecessary expenditure of fluid pumping power and of inefficiency of cooling achieved.

FIELD OF THE INVENTION The principal object of this invention is to overcome the aforesaid disadvantages and to provide, in or for a gas-liquid contacting apparatus, an improved cooling medium-moving device of the kind referred to, the operation of which under varying conditions requires the expenditure of less power than has hitherto been the case.

Another object is to provide, in or for a gas-liquid contacting apparatus, a cooling medium-moving device of the kind referred to, which enables economy of power expenditure to be achieved by reduction of speed of rotation of the turbine and fan without any substantial variation in the cooling conditions in the apparatus.

A further object of the invention is to provide in a water cooling tower, a turbine-driven fan type air-moving device operable by the water supplied to the tower for treatment therein and which enables the speed of rotation of the turbine and fan to be varied in accordance with the cooling requirements while the supply of water to the tower is maintained constant.

SUMMARY OF THE INVENTION According to this invention, there is provided, in or for a gas-liquid contacting apparatus, a cooling medium-moving device comprising at least one fluid operated turbine and a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus wherein the operating fluid supply for said turbine is distributable amongst any one or more of a plurality of flow paths to said turbine, one of which is designed to feed a nozzle or noules to effect the operation of the turbine and the other or others of which is/are designed either also to assist the driving of the turbine or to be inoperative thereon, whereby the speed of rotation of the turbine and fan may be varied by the use of one or more of said flow paths as desired.

2 BRIEF DESCRIPTION OF DRAWINGS The invention will be more readily understood from the following description taken in conjunction with the accompanying diagrammatic drawings, which illustrate some embodiments of the invention, it being clearly understood that the invention is in no way limited thereto or thereby, but that the true scope of the invention is defined in and by the appended claims. In the drawings,

FIG. 1 is a sectional elevation of part of a gas-liquid contacting apparatus, in the instance shown, a water cooling tower, which incorporates one form of a cooling medium-moving device embodying the invention;

FIG. 2 is a sectional elevation of a modified form of cooling medium-moving device embodying the invention and suitable for use in the water cooling tower of FIG. 1;

FIG. 3 is a similar view to FIG. 2, but showing a further modification of cooling medium-moving device in accordance with the invention and FIG. 4 is a similar view of a still further modification.

DESCRIPTION OF PREFERRED EMBODIMENTS ln carrying out the invention, the operating fluid supply system to the, or each turbine, preferably includes a main operating nozzle or series of nozzles through which operating fluid from a supply thereof may be passed to drive the turbine and one or more secondary nozzles or series of nozzles and/or one or more outlet apertures or series of apertures, through any one or more of which secondary nozzles or apertures part or all of said operating fluid supply may be passed as required to vary the speed of rotation of the turbine as desired.

The aperture or series of apertures is/are preferably so disposed relative to the turbine rotor that fluid issuing therefrom is not utilized to drive the turbine, but passes over or inoperatively through the turbine to be distributed thereby in the apparatus, whereby the speed of rotation of the turbine and fan and the amount of driving power supplied to the said turbine may be varied as required according to the conditions of operation and the cooling medium flow requirements.

Advantageously, fluid may be supplied to the secondary nozzle or nozzle series and/or to the aperture of aperture series by one or more branch pipes communicating with a pipe carrying the fluid supply for the main nozzle or nozzle series, each of said pipes containing valve mechanism operable to control the quantity of fluid flowing to the pertaining nozzle or noules or aperture or apertures, as the case may be.

The pressure of the fluid in the main supply pipe and the branch pipe or pipes may be independently controlled by means of a separate pump associated with each pipe.

The operating fluid supply may advantageously consist of the liquid to be treated in the contacting apparatus.

The cooling medium-moving device may advantageously be of the kind disclosed in US. Pat. No. 3,253,819 and comprising a fan attached to a water turbine through the medium of a ries of apertures formed therein.

In practice, the turbine nozzle or nozzles may be fixedly or rotatably mounted on the pertaining fluid supply pipe or pipes.

Referring now to the drawings, and first to FIG. 1 thereof, the water cooling tower partly shown in this figure comprises a tower 1 within which is housed a cooling medium, e.g., air, moving device generally indicated by the reference letter A and comprising a water turbine 2 and fan 3 rotatable in a duct la.

Within the tower l is mounted a pipe 4 connected externally of the tower l to a water supply, not shown. Upstanding from this pipe 4 within the tower l and in communication with the interior of the pipe 4 is a further pipe 5 on which is respectively, a sleeve 8 carrying at respectively the rotor 2a of the turbine pending therefrom, and the fan 3 of the opposite ends thereof 2, having blades 2b deair-moving device A.

n the lower portion a of the pipe 5 is mounted, so as to be surrounded by the turbine blades 2b, a single fixed series of nozzles 2c in communication with the interior of the pipe 5 and thus with the pipe 4 and the water supply. A short distance above the noule series 20 is arranged an internal washer or separator 9 within the turbine 2 separating the lower portion 5a of the pipe 5 from the upper portion 5b thereof and a short distance above this washer 9, but still within the area of the turbine 2, the pipe portion 5!: is formed with a pair of opposed apertures 10,10, in communication with the interior of the said pipe 5b, the upper end of which communicates with a water supply pipe 11, which constitutes a branch pipe from the aforesaid pipe 4 and through which water from the supply may be controllably passed by operation of a valve 12. 13 indicates contact packing and 14 denotes drift eliminators.

The mode of operation of the above described device will, it is thought, be readily understood.

If the valve 12 is in the closed position, operating fluid, in this instance water, will flow wholly along the pipe 4 and into the nozzle-carrying pipe portion 5a to issue from the fixed nonle series 2c and impinge on the turbine blades 2b to cause rotation of the turbine rotor 2a and with it the supporting sleeve 8 and the fan 3. Cooling air is, thus drawn upwardly through the tower l in the direction of the arrows B,B, past the contact packing 13 where it comes into contact with the water issuing from the turbine 2 as indicated by the arrows CC, and then past the drift eliminators I4 for removal of surplus moisture from the air and is finally ejected from the tower 1 through the fan duct la.

As all the operating water is supplied to the nozzle series 2c, the turbine rotor 2a and the fan 3 will be rotated at the maximum speed available from the single supply source and will thus produce a maximum cooling effect. If, however, the temperature conditions are such that a lesser cooling efiect is desirable or if for any other reason it is desirable to reduce the rate of cooling, the valve 12 may be opened so as to by-pass some of the water flow along the pipe I1 and the pipe 5, from which latter it will escape through the apertures 10,10, and fall through the turbine 2 without exerting any driving efi'ort thereon, as indicated by the arrows D.

The speed of rotation of the turbine rotor 2a and thus of the fan 3 will thereby be reduced and less air, in consequence, will be drawn in a given time through the tower 1, thereby effecting a saving in power requirements. At the same time, the supply of operating water has not been affected, which may be of considerable importance in cases where this fluid consists of cooling water used in a continuous chemical or other process and which requires to be cooled by passage through the contacting apparatus. Alternatively, by closing the valve 40, the total water supply may be by-passed through the apertures 10 in which case the turbine and fan will become stationary and the air-flow will thus be unassisted.

In the modified arrangement shown in FIG. 2, the apertures 10,10, have been omitted and, in their place, is arranged a second nozzle series carried by, and communicating with, the interior of the pipe 5b and the branch supply pipe 11. With this arrangement, the water supply may again be passed, with the valve 12 closed, wholly to the main nozzle series 2c to drive the turbine at the maximum speed available or, with the valve 12 opened, part of the supply may be passed to the second nozzle series IS, the water issuing from which is also used to drive the turbine. By this means, the power required to drive the turbine 2 may be considerably reduced, while the speed of rotation of the turbine and the fan will be sufficient to provide an air-flow only slightly less than that obtainable with the use of only the single main nozzle series 2c. Again, if desired, the pipe 4 may be closed and the total supply passed to the noules 15.

If desired, in a further modification, the apertures 10,10, need not be omitted, the second nozzle series 15, in this case, constituting an addition to the arrangement of FIG. 1. Suitable valve control means, not shown, must, of course, be provided in the pipe 50 to enable the water flow to be distributed as desired. Such an arrangement is shown in FIG. 3, which is in all other respects the same as FIG. 2 and does not require further description.

Thus, this further modification provides a number of alternative paths for the flow of the water, namely l) wholly through the main or secondary noule series 2c or 15, (2) through both noule series 2 and I5, (3) through the nozzle series 2c or 15 and the apertures 10,10, (4) through both nozzle series 2c and 15 and also through the apertures 10,10 or (5) wholly through the apertures 10,10.

While in the above, the invention has been described and shown as applied to a cooling medium-moving device having fixed turbine noules or nozzle series, it will be found to be equally applicable to the device forming the subject of copending application Ser. No. 808,l l5 filed Mar. 18, 1969 in the name of the present Applicant entitled TURBINES, now US. Pat. No. 3,589,840 granted June 29, 1971, according to which a gasor air-moving device comprises a turbine, the nozzles of which are adapted in use to rotate in a direction opposite to that of the turbine rotor, both the rotorand the nozzle-carrying shafts each carrying fan blades. Such an arrangement is illustrated in FIG. 4 as applied to the two noule series embodiment of FIG. 3.

In FIG. 4, the two nozzle series 2c and 15, instead of, as in FIG. 3, being carried by the stationary supply pipe 5 (5a and 5b), are carried by a sleeve 16 rotatably mounted in bearings 17 and 18 on the pipe 5. The upper end of this sleeve 16 carries a fan 19. The sleeve 8 carrying the turbine rotor 2a surrounds and is rotatable around this sleeve 16. The sleeve 0 is shorter than the sleeve 16, so that the fan 3, carried adjacent the upper end thereof, is located in spaced relation to, and spaced slightly below, the fan 19. The pipes 50 and 5b are provided with apertures or slots 20 and 21, respectively, to enable the operating fluid or water to pass into the two nozzle series 20 and 15, as required. The construction is in other respects similar to that shown in FIG. 3 and like reference numerals refer to like parts in the two figures.

As will be readily appreciated, the effect of this arrangement will be that, when water is supplied to the turbine rotor 2a through the nonle series 20 and, if desired, also the nozzle series 15, in the manner hereinbefore described, the issuance of water from the nozzles will, due to the fact that the nozzle series are free to rotate, produce a reaction in the nozzles, which will cause them to rotate with the sleeve 16 in a direction opposite to the direction of motion of the water, while the water impinging on the blades 21! of the rotor 2a will cause the latter to rotate in the direction of motion of the impinging water.

As a consequence, the two concentric sleeves 8 and 16 will be caused to rotate in opposite directions to one another and thus the fans 3 and 19 mounted on the respective sleeves will also simultaneously rotate in opposite directions in the fan duct 1a.

In the use of a gas-moving device embodying the invention, it will be found that, if two series of nozzles are provided and used to drive the turbine, instead of a single series, the secondary series of noules receiving, for example, say, 30 percent of the total flow, the power required to drive the turbine will be reduced by about 50 percent, while the speed of rotation of the turbine and fan will still be such as to enable the air-flow to be maintained at about percent of that obtained with the use of a single series of nozzles fed with the total water flow.

The speed of rotation of the turbine and fan may be further reduced by using the arrangement shown in FIG. 3 and closing the secondary nozzle series 15 and allowing the water passing through the branch pipe 11 to issue through the outlet openings 10,10, in the pipe 5b, in which case the air-flow will be about 70 percent of the normal total flow.

It will be appreciated that, by means of the invention, the rate of air-flow past the water issuing from the turbine may be readily controlled in accordance with the operating conditions of the cooling tower, by causing the water to issue either from a single noule series, from two nonle series, from one or two nozzle series and one or more apertures or aperture series, or

only from one or more apertures of aperture series, thereby varying the speed of rotation of the turbine and fan, and consequently the rate of air-flow, while, at the same time, under these varying conditions of operation, realizing a considerable saving in power expenditure.

Moreover, due to the fact that all the water is constantly supplied to the area of the turbine, which is located above the tower packing, all the water, whether usilised or not to drive the turbine, will flow, or be distributed, over the packing, so that the cooling efficiency of the plant will not be substantially aflected by the saving in power.

It will, moreover, be understood that additional branch supply systems connected to the operating fluid, e.g., water, supply and opening to further nozzle series carried by the aforesaid pipe within the turbine and/or to further outlet apertures in the said pipe may be provided.

While in the above some embodiments of the manner in which the invention may be carried out have been described by way of example, it is to be understood that the invention is in no way limited thereto or thereby, but that modifications may be made thereto without departing from the scope of the invention. For example, the invention is not to be regarded as limited to the use of only two separate supply pipes as described, as any desired number of additional nozzle or aperture supplying branch pipes may be provided.

It is to be understood that the invention is intended to include within its scope any gas-liquid contacting apparatus, such as a water cooling tower, incorporating a cooling medium-moving device in accordance with the invention.

What I claim is:

l. in or for a gas-liquid contacting apparatus, a cooling medium-moving device comprising at least one fluid operated turbine having a rotor, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, at least one main nozzle arrangement associated with said turbine for the passage therethrough of fluid to drive the turbine, operating fluid supply means for said turbine, said means comprising a main supply pipe for feeding fluid to said main nozzle arrangement and at least one branch pipe communicating with said main pipe, at least one secondary nozzle arrangement associated with said turbine and said branch pipe for the supply of fluid to assist the driving of the turbine at a reduced speed, and valve mechanism in said main and branch pipes operable to control the quantity of fluid flowing to the pertaining nozzle or noules, said main and secondary nozzle arrangements being both located and operating on the same side of said turbine rotor,

2. A device according to claim 1 in which at least one noule arrangement is fixedly mounted with respect to the turbine rotor and at least one other nozzle arrangement is rotatably mounted with respect to the turbine rotor.

3. In or for a gas-liquid contacting apparatus, a cooling medium moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, and operating fluid supply means for said turbine, comprising a plurality of fluid flow paths to said turbine, at least one main operating nozzle associated with said turbine and one of said flow paths through which operating fluid from a supply thereof may be passed to drive the turbine and at least one secondary nozzle associated with said turbine and with at least one other flow path through which nozzle at least part of said operating fluid supply may be passed to reduce the speed of rotation of the turbine as required, said main and secondary nozzles being both located on the same side of the turbine rotor to ensure adequate distribution of the fluid issuing therefrom.

4. A device according to claim 3 in which the fluid supply means includes at least one flow path having therein an aperture through which at least part of said fluid supply may be passed as required, said aperture being so disposed relative to said turbine that fluid issuing therefrom is not utilized to drive the turbine, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus.

In or for a gas-liquid contacting apparatus, a cooling medium moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by. the turbine for assisting the passage of cooling medium through the apparatus, and fluid supply means for said turbine comprising a plurality of fluid flow paths to said turbine, at least one operating noule associated with said turbine and one of said flow paths through which operating fluid from a supply thereof may be passed to drive the turbine and at least one other flow path having therein at least one aperture through which at least part of said fluid supply may be passed to reduce the speed of rotation of the turbine as required and said aperture being so disposed relative to the turbine that fluid issuing therefrom is not utilized to drive the turbine, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus.

6. In or for gas liquid contacting apparatus, a cooling medium-moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, at least one main nozzle arrangement associated with said turbine for the passage therethrough of fluid to drive the turbine, operating fluid supply means for said turbine, said means comprising a main supply pipe for feeding fluid to said main nozzle arrangement and at least one branch pipe communicating with said main pipe, at least one secondary nozzle arrangement associated with said branch pipe and said turbine for the supply of fluid to assist the driving of the turbine at a reduced speed, at least said branch pipe being also provided with at least one aperture located adjacent said secondary nozzle arrangement and so disposed relative to the turbine that fluid issuing therefrom is not utilized to drive the turbine, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus, and valve mechanism in said main and branch pipes operable to control the quantity of fluid flowing along said pipes.

7. In or for a gas-liquid contacting apparatus, a cooling medium-moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, at least one nozzle arrangement associated with said turbine for the passage therethrough of fluid to drive the turbine, an operating fluid supply pipe for feeding fluid to said nozzle arrangement, a branch pipe communicating with said supply pipe, said branch pipe having therein at least one aperture located adjacent said nozzle arrangement and so disposed relative to the turbine that fluid issuing therefrom is not utilized to drive the turbine thus reducing the turbine speed, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus, and means associated with said supply and branch pipes for regulating as required the quantity of fluid flowing along said pipes.

mast t s 

1. In or for a gas-liquid contacting apparatus, a cooling medium-moving device comprising at least one fluid operated turbine having a rotor, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, at least one main nozzle arrangement associated with said turbine for the passage therethrough of fluid to drive the turbine, operating fluid supply means for said turbine, said means comprising a main supply pipe for feeding fluid to said main nozzle arrangement and at least one branch pipe communicating with said main pipe, at least one secondary nozzle arrangement associated with said turbine and said branch pipe for the supply of fluid to assist the driving of the turbine at a reduced speed, and valve mechanism in said main and branch pipes operable to control the quantity of fluid flowing to the pertaining nozzle or nozzles, said main and secondary nozzle arrangements being both located and operating on the same side of said turbine rotor.
 2. A device according to claim 1 in which at least one nozzle arrangement is fixedly mounted with respect to the turbine rotor and at least one other nozzle arrangement is rotatably mounted with respect to the turbine rotor.
 3. In or for a gas-liquid contacting apparatus, a cooling medium moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, and operating fluid supply means for said turbine, comprising a plurality of fluid flow paths to said turbine, at least one main operating nozzle associated with said turbine and one of said flow paths through which operating fluid from a supply thereof may be passed to drive the turbine and at least one secondary nozzle associated with said turbine and with at least one other flow path through which nozzle at least part of said operating fluid supply may be passed to reduce the speed of rotation of the turbine as required, said main and secondary nozzles being both located on the same side of the turbine rotor to ensure adequate distribution of the fluid issuing therefrom.
 4. A device according to claim 3 in which the fluid supply means includes at least one flow path having therein an aperture through which at least part of said fluid supply may be passed as required, said aperture being so disposed relative to said turbine that fluid issuing therefrom is not utilized to drive the turbine, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus.
 5. In or for a gas-liquid contacting apparatus, a cooling medium moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, and fluid supply means for said turbine comprising a plurality of fluid flow paths to said turbine, at least one operating nozzle associated with said turbine and one of said flow paths through which operating fluid from a supply thereof may be passed to drive the turbine and at least one other flow path having therein at least one aperture through which at least part of said fluid supply may be passed to reduce the speed of rotation of the turbine as required and said aperture being so disposed relative to the turbine that fluid issuing therefrom is not utilized to drive the turbine, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus.
 6. In or for gas liquid contacting apparatus, a cooling medium-moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, at least one main nozzle arrangement associated With said turbine for the passage therethrough of fluid to drive the turbine, operating fluid supply means for said turbine, said means comprising a main supply pipe for feeding fluid to said main nozzle arrangement and at least one branch pipe communicating with said main pipe, at least one secondary nozzle arrangement associated with said branch pipe and said turbine for the supply of fluid to assist the driving of the turbine at a reduced speed, at least said branch pipe being also provided with at least one aperture located adjacent said secondary nozzle arrangement and so disposed relative to the turbine that fluid issuing therefrom is not utilized to drive the turbine, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus, and valve mechanism in said main and branch pipes operable to control the quantity of fluid flowing along said pipes.
 7. In or for a gas-liquid contacting apparatus, a cooling medium-moving device comprising at least one fluid operated turbine, a fan coupled to, so as to be driven by, the turbine for assisting the passage of cooling medium through the apparatus, at least one nozzle arrangement associated with said turbine for the passage therethrough of fluid to drive the turbine, an operating fluid supply pipe for feeding fluid to said nozzle arrangement, a branch pipe communicating with said supply pipe, said branch pipe having therein at least one aperture located adjacent said nozzle arrangement and so disposed relative to the turbine that fluid issuing therefrom is not utilized to drive the turbine thus reducing the turbine speed, but passes inoperatively over or through the turbine to be distributed thereby in the apparatus, and means associated with said supply and branch pipes for regulating as required the quantity of fluid flowing along said pipes. 